title: Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules.
abstract: Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions.
authors.affiliation: Department of Physics, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Schobesberger
authors.forename: Heikki
authors.initials: H
authors.lastname: Junninen
authors.forename: Federico
authors.initials: F
authors.lastname: Bianchi
authors.forename: Gustaf
authors.initials: G
authors.lastname: Lönn
authors.forename: Mikael
authors.initials: M
authors.lastname: Ehn
authors.forename: Katrianne
authors.initials: K
authors.lastname: Lehtipalo
authors.forename: Josef
authors.initials: J
authors.lastname: Dommen
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ehrhart
authors.forename: Ismael K
authors.initials: IK
authors.lastname: Ortega
authors.forename: Alessandro
authors.initials: A
authors.lastname: Franchin
authors.forename: Tuomo
authors.initials: T
authors.lastname: Nieminen
authors.forename: Francesco
authors.initials: F
authors.lastname: Riccobono
authors.forename: Manuel
authors.initials: M
authors.lastname: Hutterli
authors.forename: Jonathan
authors.initials: J
authors.lastname: Duplissy
authors.forename: João
authors.initials: J
authors.lastname: Almeida
authors.forename: Antonio
authors.initials: A
authors.lastname: Amorim
authors.forename: Martin
authors.initials: M
authors.lastname: Breitenlechner
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Downard
authors.forename: Eimear M
authors.initials: EM
authors.lastname: Dunne
authors.forename: Richard C
authors.initials: RC
authors.lastname: Flagan
authors.forename: Maija
authors.initials: M
authors.lastname: Kajos
authors.forename: Helmi
authors.initials: H
authors.lastname: Keskinen
authors.forename: Jasper
authors.initials: J
authors.lastname: Kirkby
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kupc
authors.forename: Andreas
authors.initials: A
authors.lastname: Kürten
authors.forename: Theo
authors.initials: T
authors.lastname: Kurtén
authors.forename: Ari
authors.initials: A
authors.lastname: Laaksonen
authors.forename: Serge
authors.initials: S
authors.lastname: Mathot
authors.forename: Antti
authors.initials: A
authors.lastname: Onnela
authors.forename: Arnaud P
authors.initials: AP
authors.lastname: Praplan
authors.forename: Linda
authors.initials: L
authors.lastname: Rondo
authors.forename: Filipe D
authors.initials: FD
authors.lastname: Santos
authors.forename: Simon
authors.initials: S
authors.lastname: Schallhart
authors.forename: Ralf
authors.initials: R
authors.lastname: Schnitzhofer
authors.forename: Mikko
authors.initials: M
authors.lastname: Sipilä
authors.forename: António
authors.initials: A
authors.lastname: Tomé
authors.forename: Georgios
authors.initials: G
authors.lastname: Tsagkogeorgas
authors.forename: Hanna
authors.initials: H
authors.lastname: Vehkamäki
authors.forename: Daniela
authors.initials: D
authors.lastname: Wimmer
authors.forename: Urs
authors.initials: U
authors.lastname: Baltensperger
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Carslaw
authors.forename: Joachim
authors.initials: J
authors.lastname: Curtius
authors.forename: Armin
authors.initials: A
authors.lastname: Hansel
authors.forename: Tuukka
authors.initials: T
authors.lastname: Petäjä
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.forename: Neil M
authors.initials: NM
authors.lastname: Donahue
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Worsnop
mesh_terms: D000336:Aerosols / Q000032:analysis / Q000737:chemistry; D000641:Ammonia / Q000032:analysis / Q000737:chemistry; D001272:Atmosphere / Q000032:analysis / Q000737:chemistry*; D004123:Dimethylamines / Q000032:analysis / Q000737:chemistry; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D013058:Mass Spectrometry; D039821:Monoterpenes / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D015203:Reproducibility of Results; D013464:Sulfuric Acids / Q000737:chemistry*; D014835:Volatilization
chemical_list: D000336:Aerosols; D004123:Dimethylamines; D039821:Monoterpenes; D009930:Organic Chemicals; D013464:Sulfuric Acids; D000641:Ammonia; C034516:dimethylamine; C033158:sulfuric acid
keywords: aerosol particles; atmospheric chemistry; atmospheric nucleation; mass spectrometry